Oxygen breathing controllers are normally used to supply oxygen to users at high altitudes. Common users are parachutists and airborne military personnel in an unpressurized aircraft. For example, a user aboard an unpressurized aircraft has the use of an oxygen supply tank, i.e., aircraft-mounted prebreather. A prebreather system supplies 100% oxygen to the user which serves to denitrify the user's blood. Utilization of the aircraft-mounted system also conserves user's personal oxygen supply for later use during a parachute descent. Before exiting the aircraft, the user switches from an aircraft-mounted prebreather to his/her personal oxygen supply.
A cabin crew member user who must perform duties during a flight may use a portable oxygen system for mobility within the aircraft cabin or may access to an aircraft-mounted prebreather to conserve oxygen in the personal supply.
Conventional controller systems have many areas that need improvement. An existing unit is CRU-79/P, which is a chest mounted, 100% oxygen, positive pressure regulator. This unit is reflective of a majority of conventional regulators using a spring-loaded diaphragm/poppet/guide/seat arrangement. Such a mechanical design has inherent problems with a leakage which is caused by a poorly-seated poppet.
Prior art breathing regulators have a problem in that approximately 10% of the volume is lost to the atmosphere. A conventional breathing regulator continuously bleeds oxygen to atmosphere even when it is not in use. The bleeding loss continues as long as the breathing regulator is connected to an oxygen source at the rate of up to 0.75 lpm. Under normal breathing conditions, a breather consumes approximately 8 lpm. Thus, a 0.75 lpm bleed rate represents a 10% volume loss to atmosphere. For a parachutist who must descend from a high altitude with a limited personal oxygen supply, a loss of 10% oxygen volume could have a significant effect.